RESUMO
The optimal dosing of intravenous tobramycin for treatment of pulmonary exacerbations in paediatric cystic fibrosis (CF) patients has not been completely delineated. We performed a retrospective study evaluating the pharmacokinetics and pharmacodynamics of once daily dosing (ODD) of IV tobramycin compared to twice daily dosing (TDD). Fifty-nine and 44 patients were included in the ODD and TDD groups, respectively. Once daily dosing achieved higher Cmax as compared to TDD (29.5 ± 11.0 vs 19.0 ± 4.9, P < 0.001), lower 24âhour AUC (92.8 ± 28.7 vs 128.5 ± 34.6, P < 0.001), and greater time that drug concentration was below the minimum inhibitory concentration (MIC) (13.4 ± 1.7 vs 3.9 ± 3.1âhour, P < 0.001). Twice daily dosing failed to achieve goal Cmax:MIC for MICs >1.0âmg/l. Twice daily dosing may be a viable alternative to ODD in treating organisms with MICs ≤ 1.0âmg/l; however, with MICs >1.0âmg/l, ODD is likely necessary to achieve goal Cmax:MIC ratios.